Posture Influences the Extent of Spread of Contrast Medium During Thoracic Epidurography: A Prospective Randomized Trial.

BACKGROUND Various factors influencing the distribution of sensory blockade in epidural anesthesia have been identified; however, reports on the effects of gravity and different postures in thoracic epidural anesthesia have been rare. Medications may be injected with the lateral decubitus or the neutral position; however, it is unclear whether the distribution range of medication is similar or significantly different between these 2 postures. OBJECTIVE We focused on identifying the effect of different postures on the distribution of local anesthetics using epidurography at the thoracic level. STUDY DESIGN Prospective randomized trial. SETTING An interventional pain management practice in South Korea. METHODS A total of 68 patients were randomized to either the L group (n = 34, lateral decubitus with neck and hip flexion) or the P group (n = 34, prone position). After completing the insertion of the epidural catheter, the location of the catheter tip was adjusted between T7 and T8 and the patients were asked to change their posture according to their allocated group. Three mL of contrast medium was injected and the total number of segments, including the most cranial and caudal ends of the vertebra, was identified. RESULTS The total number of vertebral segments confirmed by contrast medium spread was 7.4 ± 2.2 in group P and 9.2 ± 1.8 in group L. The total number and the number of vertebral segments covered in the caudad direction were higher in group L compared to group P and this was statistically significant (P < 0.001). LIMITATIONS We made every effort to make the posture of group L like crouchback, we think that slight differences would present in the flexion angles of the neck and hip among thepatients of group L. CONCLUSION Group L demonstrated a more extensive distribution of contrast medium for both the cranial and caudad directions compared to group P.Key words: Epidural, thoracic, contrast medium, injections.